ACT Data Products - Masks South 2008
The point source mask is a map, in FITS format, with the same footprint and World Coordinate System as the associated 148 GHz data. The mask is unity everywhere except in circles of 10 arcminute diameter around sources detected in the data. These sources were detected in the combined 148 GHz data from the 2008 season with a matched filter, which uses the ACT beam profile along with an estimation of the map noise. After filtering, sources detected with a signal to noise ratio of 5 and with a 148 GHz flux density of 20 mJy were identified for masking. Due to edge effects, some spurious detections are masked in regions of low hits-per-pixel. Such edge regions are generally undesirable for analysis.
To use the mask, read in both the data and the mask and multiply the data, pixel-wise, by the mask.
For more information about the matched filtering used to detect sources in ACT data, see http://adsabs.harvard.edu/abs/2011ApJ...731..100M.